Design of a soft-error robust microprocessor

The costs to protect a commercial microprocessor against soft errors are discussed in this work. Based on hardware and time redundancies, a protection scheme was designed at RT level to mitigate transient faults on combinational and memory circuits. A fault-tolerant IC version of a mass-produced 8-bit microprocessor is protected by the scheme. Design issues and results in area, performance and power are presented comparing the robust microprocessor with its non-protected version. The costs by flip-flop are also discussed permitting to estimate the overheads in area for any architecture. Furthermore, the RT-level protection scheme is compared with an electrical-level scheme based on a non-standard gate.     

Periplasmic expression of human growth hormone via plasmid vectors containing the {lambda}PL promoter: use of HPLC for product quantification

The influence of different factors acting on Escherichia coliperiplasmic expression of recombinant human growth hormone (hGH)in shake flask cultures has been investigated. Bacterial vectorscontaining the phage     

Is the Jaw Bone Micro-Structure Altered in Response to Osteoporosis and Bisphosphonate Treatment? A Micro-CT Analysis

The aim of the study was to quantify the micro-architectural changes of the jaw bone in response to ovariectomy, exposed or not to bisphosphonate treatment. A total of 47 Wistar rats were ovariectomized (OVX) or sham-operated (shOVX) and exposed to osteoporosis preventive treatment for eight weeks either with bisphosphonates (alendronate, ALN; group OVX-ALN) three days/week at a dose of 2 mg/kg or with saline solution (untreated control condition; group OVX). The bone morphometric parameters of the trabecular jaw bone were assessed using ex vivo micro-computed tomography. The regions of interest investigated in the maxilla were the inter-radicular septum of the second molar and the tuber. The regions quantified in the mandible included the three molar regions and the condyle. A one-way analysis of variance followed by pairwise comparison using Tukey’s HSD and the Games–Howell test was conducted to explore significant differences between the groups. In the maxilla, OVX decreased the bone volume in the inter-radicular septum of the second molar. Bisphosphonate treatment was able to prevent this deterioration of the jaw bone. The other investigated maxillary regions were not affected by (un)treated ovariectomy. In the mandible, OVX had a significant negative impact on the jaw bone in the buccal region of the first molar and the inter-radicular region of the third molar. Treatment with ALN was able to prevent this jaw bone loss. At the condyle site, OVX significantly deteriorated the trabecular connectivity and shape, whereas preventive bisphosphonate treatment showed a positive effect on this trabecular bone region. No significant results between the groups were observed for the remaining regions of interest. In summary, our results showed that the effects of ovariectomy-induced osteoporosis are manifested at selected jaw bone regions and that bisphosphonate treatment is capable to prevent these oral bone changes.     

Surface modification of styrene-divinylbenzene copolymers by polyacrylamide grafting via gamma irradiation

Polyacrylamide chains were grafted onto styrene-divinylbenzene (S-DVB) copolymer beads using gamma radiation from a ⁶⁰Co source by applying the simultaneous method. S-DVB macroporous copolymer was synthesized by aqueous suspension polymerization and characterized by determining apparent density, surface area, pore volume distribution and water uptake. Optical and electron microscopies were used in order to observe the copolymer morphology. The effect of parameters such as monomers concentration, irradiation dose and presence of inhibitor (Mohr’s salt) on grafting reaction was studied. The grafting reaction was evaluated with the aid of elemental analysis, FTIR, HR-MAS NMR spectrometry, thermogravimetry (TG) and electron microscopy. Grafting yield (evaluated by nitrogen content) increased with acrylamide concentration and irradiation dose increasing. However, above determined values of those parameters it is observed a tendency of decreasing on the grafting yield. The presence of Mohr’s salt inhibited the production of homopolymer as well as the progress of the grafting reaction.     

Propylene Solubility in Toluene and Isododecane

Propylene solubility in toluene and isododecane (2,2,4,6,6‐Pentamethylheptane, CA Registry# 13475‐82‐6) was measured at different temperatures and pressures, similar to the ones normally used to carry out propylene polymerizations through metallocene and Ziegler‐Natta catalysts. Experimental data were obtained with a gravimetric method, where experimental liquid phase compositions are measured at known temperature and pressure conditions. The experimental data were modeled with two different models: the Wilson excess Gibbs free energy model and an empirical model. Both modeling approaches may be recommended for analysis of kinetic data obtained for slurry propylene polymerizations in toluene and isododecane.     

Surface morphology evaluation of polymer beads based on divinylbenzene by atomic force microscopy

Macroporous poly(styrene‐co‐divinylbenzene) and poly(divinylbenzene) beads were synthesized by modified suspension polymerization in the presence of different mixtures of toluene and heptane as porogen agent. Through atomic force microscopy, it was possible to identify the microspheres and the channels between them that constitute the bead pores. It was also possible to make a comparison with the results obtained by nitrogen desorption, a traditional technique used to determine the porosity of macroporous copolymers in the dry state. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 541–551, 2002; DOI 10.1002/app.10290     

Study on emulsion copolymerization of styrene andn-butyl acrylate

Summary The emulsion copolymerization of styrene and n-butyl acrylate has been investigated. Copolymers were obtained at 70°C in the presence of sodium lauryl sulfate, an anionic micelle generator and ammonium persulfate as initiator. The ideal time of reaction, the effect of the amount of initiator, temperature and comonomer composition were also studied. The copolymers have been characterized through gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR).     

Characterization of sulfonated poly(styrene–divinylbenzene) and poly(divinylbenzene) and its application as catalysts in esterification reaction

Polymeric supports based on divinylbenzene (DVB) were prepared by aqueous suspension polymerization in presence or absence of styrene (S), using toluene and n‐heptane as diluents of the monomers. Poly(S–DVB) and poly(DVB) were sulfonated with sulfuric acid in presence of 1,2‐dichloroethane. The influence of the morphological structure of the supports and as a consequence of the catalyst on the esterification reaction of acetic acid with n‐butanol was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3616–3627, 2006